Sir Menzies Campbell called for unity to restore credibility to the Liberal Democrat party as it reeled from the resignation of its home affairs spokesman following allegations he had an affair with a rent boy.
Mark Oaten's decision to stand down from the front bench follows Charles Kennedy's resignation as leader of the party on 7 January when he admitted being treated for an alcohol problem.
The disclosure that Mr Oaten, 41, a former contender for the leadership, had allegedly paid £80 a time for sex with a man, dismayed and shocked party leaders. The party's standing in the polls has fallen to 15 per cent since Mr Kennedy resigned, and the Oaten revelations, in the News of the World, are certain to inflict more damage.
According to the paper, Mr Oaten first contacted the unnamed man - then aged 23 - in 2004 through a gay website, and they met regularly over a six-month period. On one occasion, a second male prostitute was said to have been involved.
The man told the paper: "Oaten was a regular punter for six months ... He's a very troubled man living a very dangerous double life."
Mr Oaten called his actions "an error of judgement" and asked that he and his family be given some space and privacy. Sir Menzies, the acting leader, fought to restore some authority to his battered party by urging colleagues to focus on opposing Labour and the Conservative. "My job is to restore unity," he said.
He told Adam Boulton on Sky News: "You say, 'Who are the Liberal Democrats?' I will tell you who they are. They are concerned about civil liberties, internationalism, poverty, the environment, rendition - these are the issues which lie at the heart of the political agenda. As the acting leader, I am going to make sure we pursue these issues."
In Mr Oaten's Winchester constituency, feelings were mixed about the revelations, which one friend of the MP, who did not want to be named, described as being "a bolt from the blue".
The leader of Liberal Democrat-controlled Winchester City Council, Sheila Campbell, said: "I think he is among friends here in Winchester", although she confessed that the news was "shocking"
A Liberal Democrat voter, Paul Parke, 43, from Winchester, said: "I am not particularly keen on people who deceive their family. He has got two daughters and a wife he has been deceiving in that kind of way. He is not somebody who would get my support."
Christopher Huhne, the "unknown" rival for the leadership, made it clear that Mr Oaten had to take the blame for the damage done to the party. "I think that if you're in public life and you're an MP and you take a high-profile role, then I'm afraid you're going to be subject to scrutiny," he said on BBC1's Sunday AM.
Sir Menzies said Mr Oaten should be allowed "a period of space" after the disclosures, which could end his political career.
Peter Tatchell, leader of a militant gay rights group, said: "Mark Oaten is not the only Liberal Democrat MP who has had sex with men. We are disappointed that so few Lib Dem MPs have chosen to come out."Reuse content